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  <div class="section" id="extending-via-cffi">
<h1>Extending via CFFI<a class="headerlink" href="#extending-via-cffi" title="Permalink to this headline">¶</a></h1>
<div class="highlight-python notranslate"><div class="highlight"><pre><span></span><span class="sd">&quot;&quot;&quot;</span>
<span class="sd">Use cffi to access any of the underlying C functions from distributions.h</span>
<span class="sd">&quot;&quot;&quot;</span>
<span class="kn">import</span> <span class="nn">os</span>
<span class="kn">import</span> <span class="nn">numpy</span> <span class="k">as</span> <span class="nn">np</span>
<span class="kn">import</span> <span class="nn">cffi</span>
<span class="kn">from</span> <span class="nn">.parse</span> <span class="kn">import</span> <span class="n">parse_distributions_h</span>
<span class="n">ffi</span> <span class="o">=</span> <span class="n">cffi</span><span class="o">.</span><span class="n">FFI</span><span class="p">()</span>

<span class="n">inc_dir</span> <span class="o">=</span> <span class="n">os</span><span class="o">.</span><span class="n">path</span><span class="o">.</span><span class="n">join</span><span class="p">(</span><span class="n">np</span><span class="o">.</span><span class="n">get_include</span><span class="p">(),</span> <span class="s1">&#39;numpy&#39;</span><span class="p">)</span>

<span class="c1"># Basic numpy types</span>
<span class="n">ffi</span><span class="o">.</span><span class="n">cdef</span><span class="p">(</span><span class="s1">&#39;&#39;&#39;</span>
<span class="s1">    typedef intptr_t npy_intp;</span>
<span class="s1">    typedef unsigned char npy_bool;</span>

<span class="s1">&#39;&#39;&#39;</span><span class="p">)</span>

<span class="n">parse_distributions_h</span><span class="p">(</span><span class="n">ffi</span><span class="p">,</span> <span class="n">inc_dir</span><span class="p">)</span>

<span class="n">lib</span> <span class="o">=</span> <span class="n">ffi</span><span class="o">.</span><span class="n">dlopen</span><span class="p">(</span><span class="n">np</span><span class="o">.</span><span class="n">random</span><span class="o">.</span><span class="n">_generator</span><span class="o">.</span><span class="vm">__file__</span><span class="p">)</span>

<span class="c1"># Compare the distributions.h random_standard_normal_fill to</span>
<span class="c1"># Generator.standard_random</span>
<span class="n">bit_gen</span> <span class="o">=</span> <span class="n">np</span><span class="o">.</span><span class="n">random</span><span class="o">.</span><span class="n">PCG64</span><span class="p">()</span>
<span class="n">rng</span> <span class="o">=</span> <span class="n">np</span><span class="o">.</span><span class="n">random</span><span class="o">.</span><span class="n">Generator</span><span class="p">(</span><span class="n">bit_gen</span><span class="p">)</span>
<span class="n">state</span> <span class="o">=</span> <span class="n">bit_gen</span><span class="o">.</span><span class="n">state</span>

<span class="n">interface</span> <span class="o">=</span> <span class="n">rng</span><span class="o">.</span><span class="n">bit_generator</span><span class="o">.</span><span class="n">cffi</span>
<span class="n">n</span> <span class="o">=</span> <span class="mi">100</span>
<span class="n">vals_cffi</span> <span class="o">=</span> <span class="n">ffi</span><span class="o">.</span><span class="n">new</span><span class="p">(</span><span class="s1">&#39;double[</span><span class="si">%d</span><span class="s1">]&#39;</span> <span class="o">%</span> <span class="n">n</span><span class="p">)</span>
<span class="n">lib</span><span class="o">.</span><span class="n">random_standard_normal_fill</span><span class="p">(</span><span class="n">interface</span><span class="o">.</span><span class="n">bit_generator</span><span class="p">,</span> <span class="n">n</span><span class="p">,</span> <span class="n">vals_cffi</span><span class="p">)</span>

<span class="c1"># reset the state</span>
<span class="n">bit_gen</span><span class="o">.</span><span class="n">state</span> <span class="o">=</span> <span class="n">state</span>

<span class="n">vals</span> <span class="o">=</span> <span class="n">rng</span><span class="o">.</span><span class="n">standard_normal</span><span class="p">(</span><span class="n">n</span><span class="p">)</span>

<span class="k">for</span> <span class="n">i</span> <span class="ow">in</span> <span class="nb">range</span><span class="p">(</span><span class="n">n</span><span class="p">):</span>
    <span class="k">assert</span> <span class="n">vals</span><span class="p">[</span><span class="n">i</span><span class="p">]</span> <span class="o">==</span> <span class="n">vals_cffi</span><span class="p">[</span><span class="n">i</span><span class="p">]</span>
</pre></div>
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